I am from Chicago. They did a good job recreating the feel of Chicago and the landmarks but some things are not correct, there are no mountains in the Chicago area although in northwestern and southern Illinois there are large bluffs that resemble small mountains or larger hills.
There's no bridge going from the south side to the loop, it's the big long bridge going over a large body of water towards the end, that part was also made up. The smaller bridges in the loop are definitely real though. It looks like they shrank lake Michigan and made it a limited pond or something. I recognize millennium park where the guys playing with that helicopter thing and the bean in there background, also the very end where aiden is staring at the chicago river with all the bridges, that part is also real and I recognize it
Other than that, the feel and look and some of the areas I recognize. It would be very difficult to make a complete replica 1:1 of Chicago as the metro area is gigantic. I think they did a pretty good job.